1. Field of the Invention
This invention relates generally to an infusion set for subcutaneous delivery of a selected medication or other fluid to a patient. More particularly, this invention relates to an improved infusion set having a cannula housing and a connector for connecting the cannula housing to a delivery device.
2. Description of Related Art
Infusion sets are typically used for delivering a selected medication or other fluid to a patient. Infusion sets may include a cannula, which may be relatively soft and flexible. The cannula provides a transcutaneous passageway to administer a medication or other fluid to a subcutaneous site on a patient. The cannula generally attached to a cannula housing, which may be placed on the skin of the patient when the cannula is inserted. A connector attaches to the cannula housing to connect the cannula to the fluid delivery system. The fluid delivery system is generally placed in fluid communication with the connector by way of a length of infusion tubing. Examples of fluid delivery systems are shown in U.S. Pat. Nos. 4,562,751, 4,685,903, 5,080,653, 5,097,122, which are herein incorporated by reference.
Infusion sets of the type described above are generally used to deliver medication, such as insulin, to a patient over an extended period of time. The infusion sets usually are adapted to rest on the skin of the patient. The cannula housing may remain on the patient's skin for several days, and the patient may disconnect the connector when performing certain activities, like showering. Because a patient changes infusion sets fairly frequently, it is beneficial to have an infusion set that is easy to insert, easy to connect properly, and easy to remove and dispose of.
An infusion set of the above type is described in U.S. Pat. No. 5,522,803. The infusion set comprises a cannula housing with a cannula and a needle holder to be connected to the cannula housing. The cannula housing includes two guide openings and two locking openings with shoulders for engaging barbs on locking pins of the needle holder. The needle holder includes guide pins that co-operate with the guide openings on the cannula housing. The needle on the needle holder is guided by the guide pins into the cannula housing so that the needle penetrates a membrane at the inlet of a fluid passageway of the cannula housing. The fluid passageway is in fluid communication with the cannula. Thus, when the needle penetrates the membrane, the fluid may flow through the connector into the cannula housing and then into the patient. The guide pins must be guided carefully into the guide openings, as the guide openings surround the pins on all four sides when the cannula housing and needle holder are guided together.
Another infusion set of the above type is described in U.S. Pat. No. 6,302,866. The infusion set comprises a cannula housing with a cylindrical extension and a needle holder with a guide sleeve that closely slides over the cylindrical extension. The connection must be done carefully, because the cylindrical extension fits closely into the guide sleeve. The guide sleeve surrounds a connecting needle that is guided into the passageway of the cylindrical extension. The passageway in the cylindrical extension is in fluid communication with the cannula and has a septum at its inlet that is pierced by the connecting needle. Once the septum is pierced, fluid can flow from an infusion device through the needle holder into the cannula housing and then into the patient.